JP2012163467A - Falling weight testing apparatus and calculation method of collision spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a falling weight testing apparatus which is capable of accurately measuring the displacement when a wheel is caused to collide with a target.SOLUTION: A falling weight testing apparatus 1 is provided for measuring the deformation when a wheel collides with a lateral sleeper 71. The falling weight testing apparatus 1 then includes a weight 2 which is caused to fall from an upper position toward the lateral sleeper, a wheel-type contact 3 which is provided on a lower surface of the weight and simulates a wheel, a plurality of target plates 4A, 4B, ..., horizontally drawing from the wheel-type contact, displacement meters 5, ..., each for measuring the displacement of the target plate together with the time, and an accelerometer 6 which measures the acceleration of the weight together with the time.

Description

  The present invention relates to a falling weight test apparatus used in a test for knowing deformation when a wheel collides with an object and a size of a collision spring at that time, and a collision based on a test result using the apparatus. The present invention relates to a spring calculation method.

  2. Description of the Related Art Conventionally, devices for testing deformation and strength of an object by dropping a weight onto the object or dropping the object onto the floor from above are known (see Patent Documents 1 and 2). ).

  For example, Patent Document 1 discloses a drop test apparatus used for a collision test of a large object such as an automobile. This drop test apparatus is configured not only to freely drop the weight but also to accelerate and drop the weight with an accelerating device in order to suppress the height of the column for lifting the weight.

  On the other hand, Patent Document 2 discloses a drop test apparatus that drops an object toward a floor surface. In this drop test apparatus, the posture angle during the fall of the object can be fixed so that the object does not rotate during the fall.

JP 2005-207790 A JP 2005-30938 A

  By the way, it is known that if a large earthquake occurs while the train is traveling at a high speed, the wheels of the vehicles constituting the train may be disengaged from the rail and travel on the side sleepers.

  When the vehicle wheel collides with the side sleeper due to derailment, an impact force is generated, and the vehicle is lifted by the impact force. Therefore, it is desirable to confirm the relationship between the magnitude of the impact force and the amount of vehicle jump by analysis. In that analysis, what value should be set for the collision spring between the wheel and the side sleeper? Become important.

  On the other hand, when colliding a curved surface such as a wheel, unlike a conventional drop test device that collides a plane with a flat surface, the weight is tilted while the weight collides with the object, and accurate displacement is measured. It may not be possible. Further, the displacement generated during the collision is very small compared to the total displacement from the start of falling of the weight, and it is difficult to accurately measure both displacements.

  Therefore, the present invention provides a falling weight test apparatus capable of accurately measuring displacement when a wheel collides with an object, and a method for calculating a collision spring when the wheel collides with an object. The purpose is that.

  In order to achieve the above object, a falling weight test apparatus according to the present invention is a falling weight test apparatus for measuring deformation when a wheel collides with an object, and is dropped toward the object from above. A weight, a wheel-type contact that simulates the wheel provided on the lower surface of the weight, a plurality of target surfaces that extend horizontally from the wheel-type contact or the weight, and the target surface along with time It is characterized by comprising a displacement meter for measuring the displacement of each and an accelerometer for measuring the acceleration of the weight with time.

  Here, it is preferable that the target surfaces are attached in pairs at opposing positions. Moreover, the said target surface can also be set as the structure attached to the both sides of the axle shaft direction of the said wheel-type contactor, and the both sides of an axle shaft orthogonal direction.

  Furthermore, the collision spring calculation method of the present invention is a collision spring calculation method using the falling weight test apparatus described above, wherein the wheel-type contact of the weight is performed while measuring with the displacement meter and the accelerometer. A collision start time is determined based on a step of causing a child to collide with the object, a step of calculating an average displacement from displacements of a plurality of target surfaces measured by the displacement meter, and an acceleration measured by the accelerometer. The step of calculating the amount of biting during the collision based on the average displacement at the collision start time, and the step of calculating the collision spring from the relationship between the impact force calculated from the acceleration and the amount of biting It is characterized by.

  Here, it may be configured to include a step of obtaining a plastic deformation amount of the object and a step of obtaining an elastic deformation amount obtained by subtracting the plastic deformation amount from the biting amount.

  In the falling weight testing apparatus of the present invention configured as described above, a wheel-type contact that simulates a wheel is provided on the lower surface of the weight. Further, a plurality of target surfaces are extended in the horizontal direction from the wheel-type contactor or weight, and their displacement is measured by a displacement meter. Furthermore, an accelerometer is attached to the weight.

  For this reason, even if a wheel-type contactor inclines and collides with a target object, the influence by inclination can be removed by measuring displacement with a plurality of target surfaces. In addition, by determining the collision start time from the accelerometer measurement results, use a highly sensitive displacement meter that can measure local displacement, and accurately measure the displacement when the wheel collides with an object. can do.

  Further, by attaching the paired target surfaces to the opposing positions, an assumed unidirectional inclination can be easily removed. Furthermore, by providing target surfaces on both sides of the wheel-type contact in the axle direction and on both sides in the direction perpendicular to the axle, it is possible to almost eliminate the influence of inclination in various directions at the time of collision of the wheel-type contact.

  If the relationship between the impact force with speed and the amount of biting can be grasped using the falling weight test apparatus described above, the dynamic collision spring when the traveling wheel is colliding with the object is calculated. be able to.

  Furthermore, by measuring the amount of plastic deformation of the object and subtracting it from the amount of biting, the maximum amount of elastic deformation that occurs at the time of collision can be calculated, and the impact force that matches the phenomenon that actually occurs can be calculated. An accurate collision spring can be set.

It is a perspective view explaining the composition of the falling weight test device of an embodiment of the invention. It is a perspective view explaining the composition of the railroad track which lays a rail on the horizontal sleeper arranged on the ballast. It is a front view explaining the structure of the weight of a falling weight test apparatus, and a wheel-type contactor. It is a side view explaining the structure of the weight of a falling weight test apparatus and a wheel-type contactor. It is a top view explaining the attachment position of a target board. It is a figure explaining the calculation method of the collision spring using the measurement result of the falling weight test apparatus. It is the figure which showed the relationship between an impact force and the amount of biting. It is the figure which showed the vertical behavior when a wheel drive | works on a horizontal sleeper after derailment, and the figure explaining the contact force which generate | occur | produces between a wheel and a horizontal sleeper at that time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1, 3, 4, and 5 are diagrams for explaining the configuration of the falling weight test apparatus 1 of the present embodiment. The purpose of calculating the collision spring using the test result of the falling weight test apparatus 1 will be described with reference to FIG.

  FIG. 2 is a perspective view for explaining a railroad track 7 on which a horizontal sleeper 71 is arranged. As shown in FIG. 2, the track 7 is provided on a roadbed concrete 73 made of, for example, reinforced concrete. A ballast 75 is spread on the roadbed concrete 73, and a horizontal sleeper 71 is arranged on the ballast 75 in a direction substantially orthogonal to the extending direction of the track 7.

  The lateral sleepers 71 are formed of, for example, prestressed concrete, and are arranged in parallel with a certain interval in the extending direction of the track 7. Further, rails 72 and 72 and deviation prevention guards 74 and 74 parallel to the rails 72 and 72 are laid thereon.

  Next, an analysis for simulating how the vehicle wheels running at high speed will be in a state where they are removed from the rail 72 (when derailed) will be described.

  FIG. 8 is a diagram showing an analysis result simulating a state in which the wheels of the train vehicle running at 270 km / h are derailed. Here, the “sleeper traveling case” is a case in which the wheel travels on the side sleepers 71,... After derailment, and the “flat surface traveling case” travels on a flat concrete surface after the derailment. This is the case.

  In performing such a simulation, it is necessary to set the value of the collision spring when the wheel and the side sleeper 71 (or the concrete surface) come into contact with each other. That is, the vertical displacement of the wheel shown in the lower diagram of FIG. 8 changes depending on the set size of the collision spring. For this reason, in order to faithfully reproduce the phenomenon that actually occurs, it is necessary to accurately set the value of the collision spring, in particular, the value of the dynamic collision spring that changes depending on the speed at the time of the collision.

  Therefore, using the falling weight test apparatus 1 of the present embodiment, a test that simulates a situation in which a traveling wheel collides with a lateral sleeper 71 as an object is performed, and a dynamic collision is performed using the test result. Ask for a spring.

  As shown in FIG. 1, the falling weight test apparatus 1 includes a weight 2 that drops from above toward the upper surface of the horizontal sleeper 71, a wheel-type contact 3 that is provided on the lower surface of the weight 2, and a wheel type. A target plate 4A, 4B,... As a plurality of target surfaces extending in the horizontal direction from the contact, and displacement meters 5,... For measuring the displacement of the target plates 4A, 4B,. An accelerometer 6 that measures the acceleration of the weight 2 is mainly provided.

  As shown in FIGS. 1 and 3-5, the weight 2 is a weight formed into a cylindrical shape by a magnetic material such as steel. The weight 2 is lifted to a predetermined height via an electromagnet 21 attached to the upper surface thereof.

  The electromagnet 21 can be lifted to an arbitrary height by a suspension wire 21a connected to a winder (not shown). Further, the electromagnet 21 is connected to the power cable 21b, and can be switched between the presence and absence of magnetic force by energization and interruption at an arbitrary timing.

  Then, the weight 2 attracted and lifted up to the predetermined height by the electromagnet 21 is disconnected from the electromagnet 21 by cutting off the current, and freely falls along the guide rail 11 and collides with the upper surface of the side sleeper 71. Will do. By changing the height at which the weight 2 is lifted, the speed at the time of collision can be changed.

  Further, an accelerometer 6 for measuring time and acceleration is embedded in the weight 2. The accelerometer 6 is connected to an external measuring device (not shown) by a measuring cable (not shown) so as not to hinder the free fall of the weight 2 and the measurement results are sequentially recorded in the measuring device. .

  Furthermore, engaging portions 22, 22 for moving along the guide rails 11, 11 are provided at opposing positions on the peripheral surface of the weight 2. As shown in FIG. 3-5, the engaging portion 22 protrudes in parallel to the plate-like base portion 22 b that makes the back surface abut on the peripheral surface of the weight 2 and perpendicular to the surface of the base portion 22 b. The parallel blade portion 22c and bolts 22a for fixing the base portion 22b to the weight 2 are provided.

  The parallel blade portion 22c is formed by arranging a pair of strip-shaped plate members at an interval larger than the thickness of the guide rail 11. As the distance between the parallel blade portions 22c is closer to the thickness of the guide rail 11, the weight 2 can fall straight along the guide rail 11, but the contact between the guide rail 11 and the parallel blade portion 22c becomes resistance. Therefore, there is a risk of reducing the falling speed and impact force. For this reason, a certain amount of space is provided between the guide rail 11 and the parallel blade 22c.

  The wheel-type contact 3 is formed by simulating a vehicle wheel. That is, as shown in FIG. 3, the wheel part 31 provided below the main body part 32 of the wheel-type contact 3 is formed in an arc shape like the lower part of the wheel. Moreover, as shown in FIG. 4, the width | variety of the wheel part 31 is shape | molded imitating the width | variety and curved surface of a wheel.

  As shown in FIG. 5, such a wheel-type contact 3 is attached to the weight 2 so that the longitudinal direction of the horizontal sleeper 71 coincides with the axle direction 3 </ b> B. And the engaging parts 22 and 22 are attached to the surrounding surface of the weight 2 of the axle orthogonal direction 3A orthogonal to the axle direction 3B. That is, the guide rails 11 and 11 are erected with the horizontal sleeper 71 sandwiched in the axle orthogonal direction 3A.

  Then, target plates 4A and 4B for measuring the vertical displacement of the wheel-type contact 3 are attached to the lower surface of the weight 2 as shown in FIGS. Here, as shown in FIG. 5, the target plates 4A and 4A are attached to the opposing positions with the wheel-type contact 3 in the direction orthogonal to the axle 3A sandwiched, and the wheel-type contact 3 in the direction 3B of the axle is sandwiched. The target plates 4B and 4B are attached to the opposing positions.

  The target plates 4A and 4A in the axle-orthogonal direction 3A are attached at positions slightly shifted from the center (the one-dot chain line 3A in FIG. 5) in order to avoid interference with the engaging portions 22 and 22.

  In the present embodiment, the target plates 4A, 4A, 4B, and 4B are attached so as to form a cross, and mainly the influence of the inclination in the axle orthogonal direction 3A and the axle direction 3B can be removed.

  That is, since a gap for reducing resistance due to contact is secured between the guide rail 11 and the parallel blade portion 22c, the weight 2 and the wheel-type contact 3 can be lifted, dropped, There is a risk of tilting at the time of a collision with the groove 71.

  And since the wheel part 31 is shape | molded by the circular arc shape, the wheel type contactor 3 will be easy to incline in the axle orthogonal direction 3A, if it collides with the horizontal sleeper 71. FIG. Further, the wheel-type contact 3 has a narrow width because it simulates the wheel width, and when the wheel-type contact 3 collides with the side sleeper 71, the wheel-type contact 3 tends to tilt in the axle direction 3B. For this reason, the target plates 4A and 4A (4B and 4B) are respectively arranged at opposing positions sandwiching the wheel-type contact 3 in the axle orthogonal direction 3A (and the axle direction 3B) so as to remove the influence of the inclination. .

  The target plates 4A and 4B are plate materials having such a rigidity that they do not bend when the weight 2 is dropped and during collision with the horizontal sleepers 71. Furthermore, since the lower surfaces of the target plates 4A and 4B serve as measurement reference surfaces for the displacement meter 5, they are formed on surfaces that match the characteristics of the displacement meter 5 to be used.

  This displacement meter 5 is a measuring instrument that measures the displacement of the target plates 4A and 4B in the vertical direction with time. The displacement meter 5 is connected to a measurement device (not shown) by a measurement cable (not shown), and measurement results are sequentially recorded in the measurement device.

  As such a displacement meter 5, an eddy current displacement meter, a laser displacement meter, or the like can be used. Here, since the collision when the weight 2 is dropped on the side sleeper 71 is completed in several milliseconds (about 1/1000 second), the displacement meter 5 capable of high sampling measurement with a short measurement interval is used. There is a need to.

  The eddy current displacement meter is a displacement meter using a high frequency magnetic field. That is, when a high frequency current is passed through a coil inside the displacement meter 5 to generate a high frequency magnetic field, an eddy current in a direction perpendicular to the passage of magnetic flux flows on the surfaces of the target plates 4A and 4B in the magnetic field due to electromagnetic induction. It will be. As a result, the impedance of the coil changes, and the distance can be measured by the change in the oscillation state.

  Such an eddy current displacement meter is capable of high sampling measurement with a short measurement interval. However, even if the measurement range (measurable range) is large, it is about several millimeters, so it can be applied when the amount of biting in which the wheel and the side sleeper 71 collide directly is small (the collision speed is low). .

  On the other hand, a cushioning material or the like may be installed on the surface of the horizontal sleeper 71, or the collision speed may increase, resulting in a large displacement after the wheels collide. In such a case, a high sampling laser displacement meter can be used as the displacement meter 5.

  The laser displacement meter is a displacement meter that uses the target plates 4A and 4B as reflection surfaces. Although this laser displacement meter cannot measure as high a sampling as an eddy current displacement meter even if it is a high sampling one, the measurement range can be reduced to a few centimeters. This can also be applied to cases where the amount of biting increases, such as when the image is to be processed.

  Next, a method for calculating the collision spring from the result of the test using the falling weight test apparatus 1 of the present embodiment will be described.

  First, as shown in FIG. 1, a horizontal sleeper 71 is installed between the guide rails 11 of the falling weight test apparatus 1. At this time, the longitudinal direction of the horizontal sleeper 71 and the direction between the guide rails 11 and 11 are orthogonalized.

  Subsequently, the engaging portions 22 and 22 of the weight 2 are fitted to the guide rails 11 and 11, and the weight 2 is disposed on the horizontal sleeper 71. Note that the weight 2 may be installed first, and the guide rails 11 and 11 may be raised in accordance with the positions of the engaging portions 22 and 22.

  Displacement meters 5,... Are installed directly below the target plates 4A, 4A, 4B, 4B, respectively. The displacement meter 5 is installed on an arm projecting directly below the target plate 4A (4B).

  Further, the electromagnet 21 is attracted to the upper surface of the weight 2, the suspension wire 21 a is wound up by a winder (not shown), and the weight 2 is lifted along the guide rails 11 and 11 to a set height. Then, the energization of the electromagnet 21 is interrupted, the magnetic force is extinguished, and the weight 2 is freely dropped toward the upper surface of the horizontal sleeper 71.

  Thus, the weight 2 that has started to fall freely falls in a state in which the planar position and posture are maintained within a range that can be controlled by the relationship between the guide rails 11 and 11 and the engaging portions 22 and 22.

  During the fall, the displacement meter 5 and the accelerometer 6 are always measured, and the measured values are recorded in the measuring device. Here, the time of all the displacement meters 5,... And the accelerometer 6 is synchronized, and the measurement start time is the same.

The graphs of the displacements U ₁ ,..., U ₄ shown in FIG. 6 are the measurement results of the displacements of the target plates 4A, 4A, 4B, 4B. Initially when the weight 2 is dropped, the displacement is not measured because the target plates 4A, 4A, 4B, 4B are located outside the measurement range of the displacement meters 5,. When approaching the sleeper 71, the measurement is started and the time and the displacements U ₁ ,..., U _{4 at} that time are recorded.

  On the other hand, the graph of acceleration α shown in the lowermost stage of FIG. 6 shows the measurement result of the acceleration of the weight 2. The acceleration α of the weight 2 is only a constant gravitational acceleration during free fall, and the acceleration α remains zero if the initial value is set to the magnitude of the gravitational acceleration. When the wheel-type contact 3 collides with the side sleeper 71, an acceleration α opposite to the gravitational acceleration is abruptly generated.

As described above, the test results by the falling weight test apparatus 1 include the relationship between the displacements U ₁ ,..., U _{4 of the four} target plates 4A, 4A, 4B, 4B and time, and the acceleration α of the weight 2 and A relationship with time is obtained.

Therefore, first, an average displacement U _A is calculated by removing the influence of the inclination from the _four displacements U ₁ ,..., U ₄ . In the present embodiment, an arithmetic average obtained by simply adding _four displacements U ₁ ,..., U ₄ and dividing by four is calculated as an average displacement U _A. The average displacement U _A can also be used.

On the other hand, from the measurement results of the accelerometer 6, the time at which the acceleration α showed a positive value and the collision starting time T _S, reads the time at which the acceleration α is returned to 0 as the collision end time T _E. The measurement start time and the displacement gauge 5 of the accelerometer 6, since the measurement start time of ... is set to the same, the average displacement U _A collision start time T _S is the collision at the start of the displacement, it The relative displacement difference with reference to is the biting amount V.

  Further, the impact force F can be obtained from the product of the acceleration α measured by the accelerometer 6 and the mass of the fallen object mainly composed of the weight 2. FIG. 7 is a diagram showing the relationship between the impact force F and the biting amount V. In FIG.

  If the relationship between the impact force F and the biting amount V can be obtained in this way, the value of the collision spring can be calculated by dividing the impact force F by the biting amount V. Moreover, since the value of this collision spring is a value with respect to the impact force F in the state with the speed produced by the free fall, it can be said that the value of the dynamic collision spring is calculated.

Also, when measuring the recessed depth of the transverse sleepers 71 caliper, etc. after the falling weight test, it is possible to determine the amount of plastic deformation V _P caused by the collision. Then, it is possible to determine the maximum elastic deformation amount V _E by subtracting the amount of plastic deformation V _P from the maximum amount of bite V _max as shown in FIG.

That is, as shown in FIG. 7, is different from the path L2 at the time of unloading a path L1 during loading of the impact force F, by measuring the amount of plastic deformation V _P, at the time of loading and during unloading Different values of impact springs can be set.

  Next, operations of the falling weight test apparatus 1 and the collision spring calculation method of the present embodiment will be described.

  In the falling weight test apparatus 1 of the present embodiment configured as described above, a wheel contact 3 that simulates a wheel is provided on the lower surface of the weight 2. Further, a plurality of target plates 4A, 4B,... Are extended in the horizontal direction from the wheel-type contact 3, and their displacements are measured by displacement meters 5,. Further, an accelerometer 6 is attached to the weight 2.

  For this reason, even if the wheel-type contact 3 collides with the horizontal sleeper 71 while tilting, the influence of the tilt can be removed by measuring the displacement with the plurality of target plates 4A, 4B,.

Further, by determining a collision start time T _S from the measurement results of the accelerometer 6, using high displacement gauge 5 with measurable sensitivity local displacement, when colliding wheels beside sleepers 71 Can be measured accurately. That is, the sensitivity is high displacement meter 5, for measurement range is narrow and several cm from a few mm, it is not possible to measure all to collision from falling start of the weight 2, the collision start time by the accelerometer 6 T _S Can be determined, it is not necessary to measure the displacement of the weight 2 from the start of dropping, and only the displacement at the time of collision may be measured by the highly sensitive displacement meter 5.

  Further, by attaching the paired target plates 4A and 4A (4B and 4B) to opposing positions, the assumed inclination in one direction can be easily removed. Further, by providing the target plates 4A, 4A, 4B, and 4B on both sides of the wheel-type contactor 3 in the axle direction 3B and on both sides of the axle-orthogonal direction 3A, the inclination of various directions at the time of the collision of the wheel-type contactor 3 is increased. The influence can be almost removed.

  Further, if the falling weight test apparatus 1 can be used to grasp the relationship between the impact force F with speed and the biting amount V, the movement when the traveling wheel is colliding with an object such as the side sleeper 71 will be described. A realistic collision spring can be calculated.

Further, by subtracting the amount of plastic deformation V _P of transverse sleepers 71 to the bite amount V measured after the measurement by the displacement gauge 5, it is possible to calculate the maximum elastic deformation amount V _E generated during collision.

If calculated maximum elastic deformation amount V _E generated in this way at the time of collision, the value of the collision spring during unloading can be set accurately. That is, if the amount of plastic deformation V _P is not measured, because the deformation amount at the time of unloading is excessively set the biggest amount of bite V _max, it may not be possible to determine the exact impact force However, by appropriately setting the value of the collision spring at the time of unloading, it becomes possible to calculate the impact force that matches the phenomenon that actually occurs.

  The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are not limited to this embodiment. Included in the invention.

  For example, in the above embodiment, the horizontal sleeper 71 has been described as an object. However, the present invention is not limited to this, and a wheel collides with an object other than the horizontal sleeper 71 using the falling weight test apparatus 1. It is also possible to determine the collision spring when

  Moreover, although the said embodiment demonstrated the structure by which target board 4A, 4B, ... was extended | stretched from the side of the wheel-type contactor 3, it is not limited to this, The upper surface of the weight 2 Or the structure by which a target surface is extended in a horizontal direction from a surrounding surface may be sufficient.

  Further, in the above-described embodiment, the target plates 4A, 4B,... Are attached at four positions so as to form a cross shape, but the present invention is not limited to this, and only the influence of the inclination in one direction is removed. If it is good, only one pair of target plates 4A, 4A (4B, 4B) may be arranged. Also, three or more pairs of target surfaces can be provided.

  In the above embodiment, the case where the weight 2 is freely dropped has been described. However, the present invention is not limited to this, and the weight 2 can be accelerated and dropped by an acceleration device.

DESCRIPTION OF SYMBOLS 1 Drop weight test apparatus 2 Weight 3 Wheel type contact 31 Wheel part 3A Axle orthogonal direction 3B Axle direction 4A, 4B Target board (target surface)
5 displacement gauge 6 accelerometers F impact force _{T S} collision start time _U 1, ··, _{U 4} displacement _{U A} average displacement V bite amount _{V E} elastic deformation _{V P} plastic deformation α acceleration

Claims (5)

A falling weight test apparatus for measuring deformation when a wheel collides with an object,
A weight to be dropped toward the object from above;
A wheel-type contact that simulates the wheel provided on the lower surface of the weight;
A plurality of target surfaces extending in a horizontal direction from the wheel-type contactor or the weight;
A displacement meter that measures the displacement of the target surface with time, and
A falling weight test apparatus comprising an accelerometer that measures acceleration of the weight with time.   The falling weight test apparatus according to claim 1, wherein the target surfaces are attached in pairs at opposing positions.   3. The falling weight testing apparatus according to claim 1, wherein the target surfaces are attached to both sides of the wheel-type contact in the axle direction and both sides in the direction orthogonal to the axle. 4. A collision spring calculation method using the falling weight test apparatus according to any one of claims 1 to 3,
Making the wheel contact of the weight collide with the object while performing measurement with the displacement meter and the accelerometer;
Calculating an average displacement from a plurality of target surface displacements measured by the displacement meter;
Determining a collision start time based on the acceleration measured by the accelerometer, and calculating an amount of biting during the collision based on an average displacement of the collision start time;
A method for calculating a collision spring, comprising: calculating a collision spring from a relationship between an impact force calculated from the acceleration and the amount of biting. Obtaining a plastic deformation amount of the object;
The method for calculating a collision spring according to claim 4, further comprising: obtaining an elastic deformation amount obtained by subtracting the plastic deformation amount from the biting amount.